High strength multi-layer brazing sheet structures with good controlled atmosphere brazing (cab) brazeability

Abstract

The present invention relates to aluminum brazing sheet with high levels of Magnesium in the core layer and having good Controlled Atmosphere Brazing (CAB) brazeability and suitable for use with any commercially available brazing flux, including brazing flux with or without Cesium.

1 . A multi-layer aluminum brazing sheet comprising:
 a first AA3000 series alloy interlayer comprising up to about 0.15 wt. % Mg, up to about 1.8 wt. % Mn, up to about 1.2 wt. % Si, up to about 0.9 wt. % Cu, up to about 0.20 wt. % Ti, up to about 2.0 wt. % Zn and up to about 0.7 wt. % Fe;   a core layer being positioned adjacent the first interlayer, the core layer comprising between about 1.0 wt. % and about 3.0 wt. % Mg, up to about 1.5 wt. % Mn, up to about 0.8 wt. % Cu, up to about 0.7 wt. % Si, up to about 0.7 wt. % Fe, up to about 0.15 wt. % Zr, up to about 0.25 wt. % Cr, up to about 0.2 wt. % Ti, and up to about 0.25 wt. % Zn; and   a second AA3000 series alloy interlayer adjacent to the core comprising up to about 0.15 wt. % Mg, up to about 6.0 wt. % Zn, up to about 1.8 wt. % Mn, up to about 1.2 wt. % Si, up to about 0.9 wt. % Cu, up to about 0.20 wt. % Ti, and up to about 0.7 wt. % Fe; and   an AA4000 series alloy braze liner being positioned adjacent the first interlayer such that the first interlayer is disposed between the AA4000 series alloy braze liner and the core layer.   
     
     
         2 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the core layer comprises about 0.20 to about 0.70 wt. % Si. 
     
     
         3 . The multi-layer aluminum brazing sheet according to  claim 1 , wherein the multi-alloy aluminum brazing sheet is fabricated by a simultaneous multi-alloy casting process. 
     
     
         4 . The multi-layer aluminum brazing sheet according to  claim 1 , wherein the multi-alloy aluminum brazing sheet is fabricated by a unidirectional solidification of casting process. 
     
     
         5 . The multi-layer aluminum brazing sheet according to  claim 1 , wherein the multi-alloy aluminum brazing sheet is fabricated by a fusion casting process. 
     
     
         6 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the multi-layer aluminum brazing sheet is formed into a tubestock having a thickness of between about 150 microns to about 400 microns. 
     
     
         7 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the first interliner comprises a thickness of at least 40 microns. 
     
     
         8 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the second interliner comprises a thickness of at least 40 microns. 
     
     
         9 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the core layer being selected from the group consisting of an AA3000 series and an AA5000 series aluminum alloys. 
     
     
         10 . The multi-layer aluminum brazing sheet according to  claim 1  further comprising an outer layer being positioned adjacent the second interlayer and being selected from the group consisting of an AA1000 series, an AA3000 series , an AA4000 series, and an AA7000 series aluminum alloy. 
     
     
         11 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the AA4000 series alloy braze liner comprises up to about 2.5 wt. % Zn. 
     
     
         12 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the core comprises between about 1.1 wt. % and about 3.0 wt. % Mg. 
     
     
         13 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the core comprises between about 1.5 wt. % and about 3.0 wt. % Mg. 
     
     
         14 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the core comprises between about 2.0 wt. % and about 3.0 wt. % Mg. 
     
     
         15 . The multi-layer aluminum brazing sheet according to  claim 1  wherein the core comprises between about 2.5 wt. % and about 3.0 wt. % Mg. 
     
     
         16 . A multi-layer aluminum brazing sheet product comprising:
 a first interlayer being selected from a group consisting of an AA1000-series, an AA3000-series, an AA7000-series, and an AA8000-series aluminum alloy;   a core layer disposed between the first and the second interlayers, the core layer comprising between about 1.0 to about 3.0 wt. % Mg, up to about 1.8 wt. % Mn, up to about 0.8 wt. % Cu, up to about 0.7 wt. % Si, up to about 0.7 wt. % Fe, up to about 0.25 wt. % Zn, up to about 0.15 wt. % Zr, up to about 0.25 wt. % Cr, up to about 0.2 wt. % Ti,   a second interliner being selected from a group consisting of an AA1000-series, an AA3000-series, an AA7000-series, and an AA8000-series aluminum alloy; and   an AA4000 series aluminum alloy braze liner being positioned adjacent to the first interliner the AA4000 series alloy braze liner comprising up to about 2.5 wt. % Zn.   
     
     
         17 . The multi-layer aluminum brazing sheet product according to  claim 16  further comprising wherein the core layer comprises about 0.20 to about 0.70 wt. % Si. 
     
     
         18 . The multi-layer aluminum brazing sheet product according to  claim 16 , wherein the multi-alloy aluminum brazing sheet is fabricated by a simultaneous multi-alloy casting process. 
     
     
         19 . The multi-layer aluminum brazing sheet product according to  claim 16 , wherein the multi-alloy aluminum brazing sheet is fabricated by a unidirectional solidification of casting process. 
     
     
         20 . The multi-layer aluminum brazing sheet product according to  claim 16 , wherein the multi-alloy aluminum brazing sheet is fabricated by a fusion casting process. 
     
     
         21 . The multi-layer aluminum brazing sheet product according to  claim 16  wherein the multi-layer aluminum brazing sheet product has a thickness of between about 150 to about 400 microns. 
     
     
         22 . The multi-layer aluminum brazing sheet product according to  claim 16  wherein the first interliner comprises a thickness of at least 40 microns and the second interliner comprises a thickness of at least 40 microns. 
     
     
         23 . The multi-layer aluminum brazing sheet product according to  claim 16  wherein the core alloy is selected from the group consisting of an AA3000 series and an AA5000 series aluminum alloys. 
     
     
         24 . The multi-layer aluminum brazing sheet product according to  claim 16  further comprising an outer layer being positioned adjacent the second interlayer and being selected from the group consisting of an AA 1000 series, an AA3000 series, an AA4000 series, and an AA7000 series aluminum alloy. 
     
     
         25 . The multi-layer aluminum brazing sheet according to clam 16 wherein the core comprises between about 1.1 wt. % and about 3.0 wt. % Mg. 
     
     
         26 . The multi-layer aluminum brazing sheet according to clam 16 wherein the core comprises between about 1.5 wt. % and about 3.0 wt. % Mg. 
     
     
         27 . The multi-layer aluminum brazing sheet according to clam 16 wherein the core comprises between about 2.0 wt. % and about 3.0 wt. % Mg. 
     
     
         28 . The multi-layer aluminum brazing sheet according to clam 16 wherein the core comprises between about 2.5 wt. % and about 3.0 wt. % Mg. 
     
     
         29 . The multi-layer aluminum brazing sheet product according to  claim 21  wherein the multi-layer aluminum brazing sheet product is an H2X or H1X temper. 
     
     
         30 . The multi-layer aluminum brazing sheet product according to  claim 16  wherein the multi-layer aluminum brazing sheet product has a thickness of between about 0.8 to about 1.2 mm 
     
     
         31 . The multi-layer aluminum brazing sheet product according to  claim 30  wherein the multi-layer aluminum brazing sheet product is an O temper. 
     
     
         32 . The multi-layer aluminum brazing sheet product according to  claim 16  wherein the core layer has a thickness being about 10 to about 25% of a thickness of the sheet. 
     
     
         33 . The multi-layer aluminum brazing sheet product according to  claim 1  wherein the core layer has a thickness being about 10 to about 25% of a thickness of the sheet. 
     
     
         34 . The multi-layer aluminum brazing sheet of  claim 1 , wherein the fabrication process of the multi-layer aluminum brazing sheet contains a step in which a multi-alloy layered composite ingot comprising a high-Mg core layer is cast, and whereby the multi-layer aluminum brazing sheet is suitable for Controlled Atmosphere Brazing. 
     
     
         35 . The multi-layer aluminum brazing sheet product of  claim 16 , wherein the multi-layer aluminum brazing sheet product is partially fabricated via a multi-alloy casting process, and whereby the multi-layer aluminum brazing sheet product is suitable for Controlled Atmosphere Brazing.